Optical Fiber Drive Condition Setting for Spiral Scan Distortion
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Solution Overview
Problem
Optical scanning apparatuses face challenges in setting drive conditions for fibers vibrating in two axial directions to achieve optimal spiral scan patterns, particularly when resonance frequencies and phase shifts in the x and y directions are asymmetrical, leading to potential distortion and suboptimal visual-field ranges.
Innovation Solution
A drive-condition setting device and method that measure resonance frequencies and phase shifts in both directions, adjusting drive frequencies and voltages to satisfy specific conditional expressions, and correcting phase differences to ensure the scan pattern is within a predetermined amplitude range and maintains orthogonality, thereby optimizing the visual-field range without distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If drive conditions are set based on asymmetrical resonance frequencies in x and y directions, then the scan pattern amplitude can be optimized, but distortion occurs in the spiral scan pattern
Solution Approach 1:
The patent applies asymmetry by setting different drive frequencies for the x and y directions based on their respective resonance frequencies. When the resonance frequency in the x direction (fx) differs from that in the y direction (fy), the drive frequency in the x direction (fdx) is set to fx and the drive frequency in the y direction (fdy) is set to fy, rather than using a common drive frequency. This asymmetric frequency setting compensates for the asymmetrical resonance characteristics of the fiber, thereby maintaining a circular spiral scan pattern and preventing distortion.
2Ease of operation
If a common drive frequency is used in both directions, then the system operation is simplified, but the visual-field range is reduced due to asymmetrical resonance frequencies
Solution Approach 1:
The patent changes the drive frequency parameters independently for each direction based on the resonance frequency characteristics. Specifically, when fx ≠ fy, the drive frequency in the x direction is set to fx and the drive frequency in the y direction is set to fy, rather than using a common drive frequency. This parameter adjustment enables the fiber to vibrate at its resonance frequencies in both directions, maximizing the scan amplitude and expanding the visual-field range while maintaining operational feasibility.
3Manufacturing precision
If drive voltage is increased to maximize fiber amplitude, then the scan pattern amplitude is improved, but the phase difference from 90 degrees causes spiral pattern distortion
Solution Approach 1:
The patent employs feedback by measuring the actual phase difference between the x and y direction vibrations and adjusting the drive conditions accordingly. A phase detector measures the phase difference, and when it deviates from 90 degrees, the system adjusts the drive frequency or phase to correct the deviation. This feedback mechanism ensures that the phase difference remains at 90 degrees even when drive voltages are increased to maximize amplitude, thereby preventing spiral pattern distortion and maintaining manufacturing precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables the setting of optimal drive conditions for optical scanning apparatuses, ensuring an optimal visual-field range and minimizing distortion even when resonance frequencies and phase shifts are asymmetrical, thereby improving the quality of scan patterns.
Implementation Method 1
the actuator vibrating the distal end of the fiber with a predetermined drive frequency in two axial directions including an x direction and a y direction
Implementation Method 2
the fiber optically guiding illumination light emitted from a light source and radiating the illumination light from its distal end onto an observation target
Implementation Method 3
a scan-pattern detector that detects a scan pattern of the illumination light output from the distal end of the fiber
Data Source
AI summary
A drive-condition setting device applied to an optical scanning apparatus having a fiber and an actuator that vibrates a distal end of the fiber, the drive-condition setting device detects a scan pattern of the illumination light output from the fiber, measures resonance frequencies in the x direction and the y direction of the fiber, sets a drive frequency and a drive voltage based on the resonance frequencies such that conditional expressions below are satisfied: when fx>fy, fd<fy and Vx≥Vy (1) or fd>fx and Vx≤Vy (2), and when fx≤fy, fd<fx and Vx≤Vy (3) or fd>fy and Vx≥Vy (4) where fd denotes the drive frequency, Vx denotes a maximum voltage of a X direction drive signal, and Vy denotes a maximum voltage of a y direction drive signal.